Caution is required in patients with hepatic or severe renal impairment, and dosage reduction of sildenafil may be necessary. Care is also needed in patients with anatomical deformation of the penis or haematological disorders that may predispose them to priapism. In the event of prolonged erection (for more than 4 hours), patients should seek medical assistance, as penile tissue damage and permanent loss of potency can Occur. Patients are also advised to stop taking sildenafil and seek medical advice in cases of sudden visual or hearing loss.
Sildenafil should not be given to those with loss of vision in one eye· caused by nonarteritic anterior or ischaemic optic neuopathy (NAION), regardless of whether this was in connection with previous phosphodiesterase type-5 inhibitors or not patients who experience dizziness or visual disturbances should not drive or operate hazardous machinery.
The safety of sildenafil is uncertain in patients with severe hepatic impairment, bleeding disorders, active peptic ulceration, hypotension, hypertension, a recent history of stroke, myocardial infarction, or life-threatening arrhythmia, unstable angina, heart failure, or retinal disorders such as retinitis pigmentosa (a minority of whom have genetic disorders of retinal phosphodiesterases). It is advises that it should not be used in these groups.
Cardiovascular disease: For mention of a consensus statement on the use of sildenafil in patients with cardiovascular. See previously.
Use in Pregnancy & Lactation: Sildenafil is not indicated for use in newborns, children, or women.
Pregnancy Category B: No evidence of teratogenicity, embryotoxicity or fetotoxicity was observed in rats and rabbits which received up to 200 mg/kg/day during organogenesis. These doses represent, respectively, about 20 and 40 times the MRHD on a mg/m2 basis in a 50 kg subject. In the rate pre and post natal development study, the no observed adverse effect dose was 30 mg/kg/day given for 36 days. In the nonpregnant rat the AUC at this dose was about 20 times human AUC. There are no adequate and well-controlled studies of sildenafil in pregnant women.
Use in Elderly: Healthy elderly volunteers (65 years or over) had a reduced clearance of sildenafil Since higher plasma levels may increase both the efficacy and incidence of adverse events, a starting dose of 25 mg should be considered.